The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 19, 1977
Filed:
Dec. 29, 1975
Applicant:
Inventor:
Elbert N Shawhan, West Chester, PA (US);
Assignee:
Sperry-Sun, Inc., Sugar Land, TX (US);
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H04B / ;
U.S. Cl.
CPC ...
328167 ; 307246 ; 329122 ;
Abstract
A lock-in filter that may be used to detect an AC data signal in the presence of high level noise signals that may occur in such systems as those used for acoustical telemetry in boreholes includes a pair of parallel capacitors receptive of the data and noise signals and circuitry operating in response to signals in the capacitors for alternately switching the capacitors to receive the noise and data signals in phase with the data signal.